Logging Interpretation Methods Of Anisotropic Reservoir In Horizontal Well

With the rapid development of the petroleum industry,oil and gas exploration development is developing to the complex reservoirs,such as thin layer,tight sandstones reservoir and fractured reservoir etc.Horizontal well technology is applied more and more widely all over the world.However,the response of tool in horizontal well is very different from vertical well,especially the response of the resistivity tool.The distribution of the medium resistivity is no more the axial symmetry along the wellbore in horizontal well,which is different from the vertical well.As a result,the effect of formation anisotropy becomes more and more prominent.Finally,the formation anisotropy must be considered in petroleum evaluation.In this paper,we use “core scale logging technology”,comprehensive anisotropic theoretical method and analysis and calculation of experimental data,combine simulate computation of resistivity anisotropy to study the well logging interpretation and evaluation of anisotropic reservoir in horizontal well.Generally,the formation is VTI medium in horizontal well logging environment.Based on the difference between the horizontal well and the vertical well,the different well logging responses between horizontal well and vertical well are analyzed by using well logging interpretation theoretical basis.On the whole,the resistivity of horizontal well is 21.8~49.2?·m,which is greater than that of vertical well(18.3~21.2?·m)in the case of the same formation porosity and saturation.Resistivity anisotropy is simulated by resistivity anisotropy theory.The results demonstrate that resistivity is affected by relative dip angle and formation anisotropic ratio,the more relative dip angle and anisotropic ratio,the more effect of anisotropy.Based on experimental study,the formation anisotropy is expounded by experimental data,such as electrical parameters,porosity and permeability,P-wave and S-wave time difference,capillary pressure data and granularity data.Anisotropic change law is obtained by calculation result of electrical parameters,and it is the same as the calculation result of theory model when they are compared with each other.Anisotropy coefficient is 1.1~1.3 when porosity distribution is 6~10%.Calculation models are set up by both of wire-line logging data and electrical imaging data,the method can be used to identify the formation boundary because of the higher axial resolution than that of vertical well,the results of calculation show that the extreme value is found on the formation boundary.In addition,method of "Double electrical parameters" is applied to interpretation of water flooded layer in Tarim oil field and interpretation of tight oil in Jilin oil field.The interpretation results are the same as not only oil test and production data,but also the calculation results of experiment simulation."Butterfly charts" can be used to confirm level of water flooded layer and identify crack.Combined regional geological data,horizontal well logging data and data of nearby vertical well,it can be used to well design and trajectory adjustment,and it also can be used to guide to horizontal well fracturing.With the analysis of physical change law of anisotropic reservoir and calculation of anisotropic parameters in horizontal well,it is greatly significant to the horizontal well logging interpretation.What's more,it can provide effective means for the horizontal well wire-line logging interpretation in anisotropic reservoir.